Abstract : A system useful in boresight calibration of a launch cell is provided. The launch cell has a central longitudinal axis coincident with a central longitudinal axis of a projectile that it would support. The launch cell terminates at either end thereof in a door where each door is provided with a hole through which the projectile can pass. The center of the hole is coincident with the central longitudinal axis of the launch cell. The present invention positions a boresight calibration tool relative to the central longitudinal axis of the launch cell. An open-ended first tube is sized for engagement in the hole. The first tube terminates at a first end thereof in a flange that abuts the door when the first tube is inserted into the hole from one side thereof. An open-ended second tube is sized for engagement in the hole from the other side thereof. The second tube terminates at a first end in a flange that is adjacent the door when the second tube is inserted into the hole. The second tube also includes means for supporting a variety of boresight calibration tools at the first end thereof. The first tube is coupled to the second tube when they are engaged in the hole. Provision is made to adjust the spacing between the flange of the second tube and the door in order to 'square up' the system. The system remains square even when boresight calibration tools are interchanged.